Cutting metal, particularly iron and steel, is often done with an oxygen-acetylene torch that melts and cuts the metal into pieces. Cutting with a torch that is readily portable enables metal cutting at locations where other types of metal cutting machinery are unavailable or impractical. A particular metal cutting operation that is well suited to the oxygen-acetylene torch is the cutting of lengths of large diameter pipe. Large diameter pipe, especially in the range of 8 inches through 24 inches in diameter, is used for the conveying of liquids and gases. Construction of pipelines, that is an assembly of multiple lengths of large diameter pipe, involves cutting the length needed from a standard pipe length as purchased from a pipe manufacturer or distributor.
In prior metal cutting practice, the length of pipe needed for a pipeline installation is cut with the torch being held manually by a skilled iron worker. Since the length and diameter of the pipe makes it necessary to allow the pipe to remain stationary, the metal worker must move the torch around the diameter of the pipe. This situation results in the line of cutting to be somewhat irregular, and attempting to make the line of cutting smooth and straight causes the cutting process to be somewhat slow. Pursuant to cutting, the resultant pipe length is typically welded to a fitting. With the current manually controlled cutting process, the weld may contain imperfections. These imperfections are evaluated by x-ray examination and, if serious, may require re-cutting and re-welding. The problems described cause a pipe construction project to be less than optimally efficient and may potentially produce an inferior finished result.